No power at dash/ignition

[Jdcolby]

Hello. New to tractors and this thread. I have a yanmar ym1700. Starter went bad in December 2021. The wire from the solenoid to the starter burnt up one day and the tractor ended up shutting down.
Had the starter rebuilt. Installed it and hooked the connectors to the starter backwards. Connected the battery and the engine started turning over, trying to start. The negative cable wouldn’t come off so it tried to start for maybe 20-30 seconds before I could get it off the terminal.
Swapped the wires at the started, reconnected the battery and tried to start the tractor. Nothing. No power at the dash, at all. No headlights. Nothing. 12.8v at battery and at starter. Nothing at the ignition switch. I’m lost. Any ideas? Thank you,
Jon

 

[Roadworthy]

Welcome to TBN. I suspect your tractor is old enough there are minimal (if any) electronics to fry. Start with the easy stuff and check your fuses. If you can score a schematic you might try to determine if you have any fusible links as well. It is possible you have fried your voltage regulator or a diode in the alternator but I'd start with the cheap stuff - fuses.

 

[richriddle]

Here is a wiring diagram for a generic old Yanmar. Assuming the wiring is original, the wire you are looking for is a WHITE wire with a RED stripe (thick ten gauge). The WHITE wire with a RED stripe begins at the starter solenoid and shares the same post as the POSITIVE battery cable.

1. First ensure the WHITE wire with RED stripe is attached to the same lug as the POSITIVE cable from the BATTERY and your starer solenoid. The POSITIVE cable is always HOT; be careful.

2. From the lug on the starter solenoid, the WHITE wire with RED stripe should go to the generator/alternator, so measure the voltage there.

3. After the WHITE wire with RED stripe leaves the generator/alternator, it goes to the VOLTAGE REGULATOR. The voltage regulator on the YM276D is on the left side of the tractor on the metal "firewall" above the starter. It has a plug on it. Measure the voltage there. A voltage regulator cost about $25 many places including here: Yanmar Voltage Regulator

4. From the VOLTAGE REGULATOR, the WHITE WIRE with RED STRIPE feeds your ignition switch and should be HOT at ALL TIMES. Check for voltage there on the "B" connection.

5. The IGNITION SWITCH feeds the Yanmar fuse panel off of the "BR" connection using a WHITE WIRE with BLACK STRIPE. With the IGNITION SWITCH in the "on" position you can meter the WHITE WIRE with the BLACK STRIPE where the wire feeds into the fuse box.

6. Check your FUSES.

 

[rScotty]

Some things don't make sense to me here. In the first place, the owner says that the wire from the solenoid to the starter burned up. That's weird. Some solenoids did have a short stubby wire a few inches long connecting between the solenoid and the starter, so I'm guessing that's the one he means, but it is one very heavy wire. But usually instead of a wire, the connection from solenoid to starter is a bus bar a few inches long. If it is a wire, it had to be the same diameter as a battery cable. That must have been some serious heat. For that wire to burn up, the short circuit had to happen within the starter case itself. I'm surprised there was anything left to rebuild.

BTW, did we find out if his tractor has a generator or alternator? The wiring is is a little different & so are the wire colors. Or someone may have changed it and used different wiring.

Just hooking up the battery backwards for an instant can often be fixed pretty easily with some polarization in old style systems. In those old style generators and voltage regulators needed to be polarized in the running direction. That went for some starters as well.

However, If it is an old style (with generator instead of alternator) and hooked up backwards for more than a fraction of a second then the voltage regulator is probably ruined. Maybe other parts. It's hard to know.

Frankly I would concentrate on getting it running and leave the charging system until later. Polarize the starter field coils properly, including the solenoid. Check the solenoid operation, check the fuses, Label and disconnect the charging system.

Instead of going through every system now, if he simplifies to just an on/off switch to the solenoid plus the starter then he can start and run the tractor. That will make it much easier to troubleshoot the rest and will get it going. A diesel tractor without lights doesn't really need a charging system like a gas engine does. A battery alone will start most tractors dozens of times and can be recharged overnight.
rScotty

 

[rScotty]

Rich, your schematic shows an old style generator wiring system - the kind of generator with a rotor having commutator slots and brushes. But the photo of the voltage regulator is of the style used a generation later. I believe it is the type used with some alternators, not the type originally used with the generator. Note the blue wires.

Yanmar electrics are difficult because they used a wide variety of charging systems including some hybrids of their own. I've seen three different voltage regulators used with their alternators and I'll bet there are others.
rScotty

 

[California]

FWIW here's the back side of the dashboard of a YM240, YM1700's near twin.

(Ignore the rats nest of glass fuses I installed in place of then-unobtainable tiny original fuses).

There's really not much going on, under there.

YM240 (US) and I assume YM1700 (Japan) used the same generator and regulator as 1973 Datsun (non a/c) so replacements are cheap and easy to find.

And for future reference if someone needs it, here's the underside of YM186D dashboard.

https://www.tractorbynet.com/forums/attachments/p1640417ym186drundersidedashboard-jpg.280630/

 

[bmaverick]

Hello. New to tractors and this thread. I have a yanmar ym1700. Starter went bad in December 2021. The wire from the solenoid to the starter burnt up one day and the tractor ended up shutting down.
Had the starter rebuilt. Installed it and hooked the connectors to the starter backwards. Connected the battery and the engine started turning over, trying to start. The negative cable wouldn’t come off so it tried to start for maybe 20-30 seconds before I could get it off the terminal.
Swapped the wires at the started, reconnected the battery and tried to start the tractor. Nothing. No power at the dash, at all. No headlights. Nothing. 12.8v at battery and at starter. Nothing at the ignition switch. I’m lost. Any ideas? Thank you,
Jon

The Parts Manual and electrical schematic can be found here:

Yanmar - Model Cover Pages

YM1700 Originally a Tree Frog. 🤑 A real cheesy production logo. In a rare instance, a YM1700 Tree Frog restored to showroom new condition. This is a beauty. The machine was on a market place, the only image left in the cache to pull from. It would have been great to have more...

www.tractorbynet.com

Just scroll thru the YM1700 2 postings. There are more than 1 manual because it came in Tree Frog and in Red Apple types.

 

[Jdcolby]

Some things don't make sense to me here. In the first place, the owner says that the wire from the solenoid to the starter burned up. That's weird. Some solenoids did have a short stubby wire a few inches long connecting between the solenoid and the starter, so I'm guessing that's the one he means, but it is one very heavy wire. But usually instead of a wire, the connection from solenoid to starter is a bus bar a few inches long. If it is a wire, it had to be the same diameter as a battery cable. That must have been some serious heat. For that wire to burn up, the short circuit had to happen within the starter case itself. I'm surprised there was anything left to rebuild.

BTW, did we find out if his tractor has a generator or alternator? The wiring is is a little different & so are the wire colors. Or someone may have changed it and used different wiring.

Just hooking up the battery backwards for an instant can often be fixed pretty easily with some polarization in old style systems. In those old style generators and voltage regulators needed to be polarized in the running direction. That went for some starters as well.

However, If it is an old style (with generator instead of alternator) and hooked up backwards for more than a fraction of a second then the voltage regulator is probably ruined. Maybe other parts. It's hard to know.

Frankly I would concentrate on getting it running and leave the charging system until later. Polarize the starter field coils properly, including the solenoid. Check the solenoid operation, check the fuses, Label and disconnect the charging system.

Instead of going through every system now, if he simplifies to just an on/off switch to the solenoid plus the starter then he can start and run the tractor. That will make it much easier to troubleshoot the rest and will get it going. A diesel tractor without lights doesn't really need a charging system like a gas engine does. A battery alone will start most tractors dozens of times and can be recharged overnight.
rScotty

this is the rebuilt starter. There is a guy in a town nearby that is amazing at rebuilding auto/tractor electronics.

 

[Jdcolby]

Here is a wiring diagram for a generic old Yanmar. Assuming the wiring is original, the wire you are looking for is a WHITE wire with a RED stripe (thick ten gauge). The WHITE wire with a RED stripe begins at the starter solenoid and shares the same post as the POSITIVE battery cable.

1. First ensure the WHITE wire with RED stripe is attached to the same lug as the POSITIVE cable from the BATTERY and your starer solenoid. The POSITIVE cable is always HOT; be careful.

2. From the lug on the starter solenoid, the WHITE wire with RED stripe should go to the generator/alternator, so measure the voltage there.

3. After the WHITE wire with RED stripe leaves the generator/alternator, it goes to the VOLTAGE REGULATOR. The voltage regulator on the YM276D is on the left side of the tractor on the metal "firewall" above the starter. It has a plug on it. Measure the voltage there. A voltage regulator cost about $25 many places including here: Yanmar Voltage Regulator

4. From the VOLTAGE REGULATOR, the WHITE WIRE with RED STRIPE feeds your ignition switch and should be HOT at ALL TIMES. Check for voltage there on the "B" connection.

5. The IGNITION SWITCH feeds the Yanmar fuse panel off of the "BR" connection using a WHITE WIRE with BLACK STRIPE. With the IGNITION SWITCH in the "on" position you can meter the WHITE WIRE with the BLACK STRIPE where the wire feeds into the fuse box.

6. Check your FUSES.

I believe this is the voltage meter? Not positive, however, the location matched your discription. Looks original to me. I bought the tractor and it had been gone through and fixed up.

 

[Jdcolby]

Again, new to all of this. I assumed this motor has an alternator. Maybe it’s a generator?